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Marshall Acton II Column: No Sound, LEDs or 3.3V Output - Seeking Schematic & Help

xxcxx 3489 8
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  • #1 20374244
    xxcxx
    Level 9  
    Hi
    I have Marshall Acton II column, it does not give anything, not even sound,
    without the LEDs. I've already disassembled it and I've been checking, it has 18V at the output of the power supply that connects the main board.
    From the main board connect the board where we have power button and sound control, bass, treble ....!
    And on that board there should be a voltage of 3.3 V at a point that comes from the main board and there isn't...
    I've tried to see voltages on the main board. The BT module turns on because I can detect it with the phone and turn it on but there is no sound (nor the LEDs on the top plate, as I said)

    Does anyone have any help? any schematics for this column? I'm desperate ...


    Marshall Acton II Column: No Sound, LEDs or 3.3V Output - Seeking Schematic & Help
    Marshall Acton II Column: No Sound, LEDs or 3.3V Output - Seeking Schematic & Help Marshall Acton II Column: No Sound, LEDs or 3.3V Output - Seeking Schematic & Help Marshall Acton II Column: No Sound, LEDs or 3.3V Output - Seeking Schematic & Help Marshall Acton II Column: No Sound, LEDs or 3.3V Output - Seeking Schematic & Help
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  • #2 20870971
    mvlahovic76
    Level 5  
    Try changing the 3.3V voltage regulator TPS54335A. I have a short circuit on it. I replaced it, got 3.3V but it still doesn't work. Maybe you will have better luck!
    Close-up of a PCB with a marked area indicating a fault.
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  • #3 21502106
    OrionOfCreation
    Level 2  
    Hello, I have the exact same problem as you XXCXX. Did you find a solution?
    best regards
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  • #4 21502154
    mvlahovic76
    Level 5  
    3.3V worked but unfortunately I was unlucky, the processor had no life. I replaced the entire board because there was no time to look for a solution. The customer was demanding and didn't want to waste time.
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  • #5 21502227
    OrionOfCreation
    Level 2  
    Sad story haha
    simple question if I may, how did you know the STM32 was dead ?
  • #6 21502248
    mvlahovic76
    Level 5  
    >>21502227 There is a small quartz crystal oscillator next to the processor that gives it a clock. Measure (best with an oscilloscope) whether it has a sine signal. I don't remember what frequency it was, but it has a label. In my case, there was nothing and the processor had a 3.3V power supply after replacing the voltage regulator. The assumption was that it was damaged due to a regulator breakdown. Oh yes, I forgot to mention that the problem is also possible in the firmware. As I wrote, I didn't have much time to investigate because of an impatient customer. Be sure to check that there is no other short circuit anywhere else in the second power supply if your 3.3V is active. The output amplifier can also cause a problem because it is most often damaged and the protection does not allow the device to turn on.
  • #7 21502268
    OrionOfCreation
    Level 2  
    Thanks a lot, I'll take a look at him tomorrow. My voltage regulator was ok, let's hope the processor too :finger_cross:
    Thanks for your help
  • #8 21502548
    Elektromonterek
    Level 24  
    >>21502248
    One question for you: Where did you get new board for it? I tried contact marshall but they wont sell any parts. Maybe you have some authorised service access and can buy them somehow?
    I have Woburn II and Acton II also with the same - i think firmware failure in STM32. All voltages are ok, no power.
    Thanks for any info.
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Topic summary

The Marshall Acton II column exhibits a failure to produce sound, illuminate LEDs, or provide the expected 3.3V output on the control board despite receiving 18V from the power supply. The Bluetooth module powers on and pairs with devices, indicating partial functionality. Troubleshooting suggests the 3.3V voltage regulator (TPS54335A) may be faulty; replacing it restored 3.3V but did not resolve the issue. Further diagnosis points to a potentially dead STM32 microcontroller, evidenced by the absence of a clock signal from the adjacent quartz crystal oscillator. Firmware corruption is also considered a possible cause. Additional checks include verifying no short circuits on the secondary power supply and inspecting the output amplifier, which may trigger protection circuits if damaged. Replacement of the main board was ultimately chosen by one user due to time constraints and unavailability of official parts from Marshall. Alternative sourcing options such as third-party sellers on platforms like AliExpress were mentioned.
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